Typical pyrotechnic airbag systems are used in almost all modern vehicles. The actual bag, which cushions the occupant of the vehicle in the event of a crash, is filled with hot gas. This gas is formed by a combustion reaction of material in tablet form in the so-called gas generator.
The inflation process depends on the chemical properties and the geometry—essentially the surface area—of the material. Airbags may be adjusted “adaptively” by igniting a second charge of the material and/or opening a valve in the bag or in the generator, so that gas escapes or is not even directed into the bag.
Alternatively, cold gas airbags, which fill the bag with a gas from a pressurized volume, may be used.
There are also hybrid systems using cold gas and pyrotechnic components.